Magneto-optical recording medium

Abstract

A magneto-optical recording medium is disclosed with which magneto-optical recording is performed by a magnetic-field modulation method and which enables stable recording characteristics to be realized even if the intensity of the recording magnetic field is somewhat changed. When a magneto-optical recording medium incorporating a signal recording layer made of TbFeCoCr and arranged such that a magneto-optical recording operation is performed with respect to the signal recording layer by the magnetic-field modulation method is manufactured, the signal recording layer is formed such that the total quantity of Tb and Cr contained in the signal recording layer is 24±1 at %. After the signal recording layer has been formed, exposure to stem by 30x10-6 Torr.sec to 10000x10-6 Torr.sec or exposure to oxygen by 10x10-6 Torr.sec to 50x10-6 Torr.sec is performed to oxidize the surface of the signal recording layer.

What is claimed is:  
     
       1. A magneto-optical recording medium comprising: 
       a disc substrate on which a first dielectric layer, a signal recording layer constituted by a thin film made of an alloy of a rare earth element and transition metal, an oxidized layer formed by oxidizing the surface of said signal recording layer after the signal recording layer is formed, a second dielectric layer, a light reflecting layer and a protective layer are sequentially formed so that magneto-optical recording of said signal recording layer is performed by a magnetic-field modulation method, wherein  
       said signal recording layer is made of TbFeCo and Tb is contained in said signal recording layer in a quantity of 23.5±1 at %.  
     
     
       2. A magneto-optical recording medium according to claim  1 , wherein 
       a first dielectric layer, a signal recording layer constituted by a thin film made of an alloy of a rare earth element and transition metal, an oxidized layer formed by oxidizing the surface of said signal recording layer, a second dielectric layer, a light reflecting layer and a protective layer are sequentially formed on said disc substrate so that magneto-optical recording of said signal recording layer is performed by a magnetic-field modulation method, and  
       a recording operation is performed with the intensity of a recording magnetic field which satisfies a range from 100 Oe to 300 Oe.  
     
     
       3. A magneto-optical recording medium according to claim  1 , wherein 
       a first dielectric layer, a signal recording layer constituted by a thin film made of an alloy of a rare earth element and transition metal, an oxidized layer formed by oxidizing the surface of said signal recording layer, a second dielectric layer, a light reflecting layer and a protective layer are sequentially formed on said disc substrate so that magneto-optical recording of said signal recording layer is performed by a magnetic-field modulation method, and  
       a pit and projection pattern corresponding to servo signals and address signals and a pit and projection pattern corresponding to lands and grooves formed along recording tracks or meandered lands and grooves are provided for said disc substrate.  
     
     
       4. A method of manufacturing a magneto-optical recording medium which incorporates a signal recording layer made of TbFeCoCr so that magneto-optical recording of said signal recording layer is performed by a magnetic-field modulation method, said method of manufacturing a magneto-optical recording medium comprising the steps of: 
       forming said signal recording layer such that the total quantity of Tb and Cr contained in said signal recording layer is 24±1 at %; and  
       then, exposing said formed signal recording layer to steam at 30×10 −6  Torr·sec to 10000×10 −6  Torr·sec or oxygen at 10×10 −6  Torr·sec to 50×10 −6  Torr·sec so that the surface of said signal recording layer is oxidized.  
     
     
       5. A method of manufacturing a magneto-optical recording medium which incorporates a signal recording layer made of TbFeCo so that magneto-optical recording of said signal recording layer is performed by a magnetic-field modulation method, said method of manufacturing a magneto-optical recording medium comprising the steps of: 
       forming said signal recording layer such that the total quantity of Tb contained in said signal recording layer is 23.5±1 at %; and  
       then, exposing said formed signal recording layer to steam at 30×10 −6  Torr·sec to 10000×10 −6  Torr·sec or oxygen at 10×10 −6  Torr·sec to 50×10 −6  Torr·sec so that the surface of said signal recording layer is oxidized.